TORONTO -- After one game and two rigorous practices, it was clear to Randy Carlyle that the Toronto Maple Leafs had to be more conservative and get back to playing a skating game in order to be successful.

After his home debut Tuesday against Boston, it's clear that Toronto's new coach has a heck of a lot more work to do.

The Bruins spoiled Carlyle's first game behind the home bench at Air Canada Centre with a 5-4 victory. Their top line of David Krejci, Tyler Seguin and Milan Lucic piled up four more points, giving them 18 in the four games since they were put together, and Jordan Caron had a career-best 3-point game after recording his first career two-point game in Sunday's loss in New York.

"We need a lot of guys to step up right now," Bruins coach Claude Julien said. "We're battling some injuries, so we just need our team to really grind it out, understand that we may not have our full squad and from here on in it may be a challenge to win every game but this is what is going to build some character moving forward. I'm hoping we take advantage of the situation to do just that."

It was a cringe-worthy type of game for the defensive-minded Carlyle. The former Norris Trophy winner watched the Leafs blow assignments in their own zone and leave goalie Jonas Gustavsson hung out to dry far too often. On top of it, the Maple Leafs, who are still 12th in the Eastern Conference, five points back of the idle eighth-place Winnipeg Jets with 16 games left, also lost Joffrey Lupul and Colby Armstrong to injuries.

Both players left the game in the second period. Carlyle said Lupul suffered an upper-body injury after getting hit by Krejci in the corner and is likely out for Wednesday's game in Pittsburgh. Armstrong hurt his nose after a fight with Boston defenseman Dennis Seidenberg and his status is also up in the air, though Carlyle wouldn't rule him out for the game against the Penguins.

Carlyle wouldn't mind ruling out the sour defensive zone coverage that led to Boston having easy scoring chances around the net. Boston's first four goals were all scored from right around the blue paint on a tip-in (Caron), a deflection (Seguin), a put-back (Chris Kelly) and a one-timer (Caron).

"They can't continually give up quality scoring chances. Those are the things we have to correct as a group," Carlyle said. "That's all part of the process here with this hockey club. We got enough goals to win the hockey game; it's the defensive aspect of it that needs to be improved upon.

"Everybody knew that this team could score goals, or has had the history of scoring goals this season, and tonight was another indication of the amount of work necessary on the defensive side of it, the compete side of it and the one-on-one battles side of it."

Carlyle liked what he saw from his group in the third period as it tried to battle back from a 5-3 deficit. Mikhail Grabovski scored with 6:47 remaining to slice the lead to 5-4 and the Leafs continued to pressure and earned two power-play opportunities in the final 5:06. They couldn't convert for the tying goal.

"We scored enough goals to win the game; we just have to tighten up in our end," Leafs captain Dion Phaneuf said. "We're going to work at it. At this time of the year we don't want to be making mistakes that cost us games. We're going to have to learn, but the good thing about this is we've got another game in less than 24 hours and we're going to have to turn it around."

Most of the Bruins' damage was done in a wild second period that included six goals, three fights, 10 penalties totaling 32 minutes, and the injuries to Lupul and Armstrong.

Toronto grabbed a 2-1 lead with John-Michael Liles' power-play goal just 57 seconds into the period, but Seguin and Kelly scored 41 seconds apart to give the Bruins a 3-2 lead before three minutes had elapsed in the period. Kelly banged home a loose puck that was in the slot, an opportunity created when Caron bulled his way past Luke Schenn to get a shot on Gustavsson.

Lupul, Phil Kessel and Tyler Bozak were on the ice for both goals against. Carlyle said it was a key turning point in the game.

Kessel, in fact, finished with a goal and an assist but was a minus-2 in over 22 minutes of ice time. He scored on a 5-on-3 with 10:08 left in the second period to make it 3-3.

Caron and Seguin came back with goals separated by 2:35 later in the period to give Boston its two-goal lead.

"Any time you score four goals you should feel good about your offensive side of it," Carlyle said, "but defense wins at this time of the year."

Julien wants to the Bruins to get back to winning by committee, which was the identity that made them Stanley Cup champions last year. Tuesday was a good sign that it's coming back as 11 of Boston's 18 skaters had at least a point and all but three had a shot on goal.

"We didn't win the Stanley Cup because one player was great. It was about committee and everybody participated at some point," Julien said. "This is what we need to rediscover again. If we want to find that identity that we had last year, we've got to start by getting our work ethic back to that level and keep pushing for each other, keep working hard and at the end of the night tell yourself that you outworked the other team."